Production of free-flowing particles of glucose, fructose or the mixture thereof

ABSTRACT

Free-flowing particles of glucose, fructose or mixtures thereof are produced by kneading an anhydrous powder of the sugar with a 40-90% by weight solution of said sugar to give a kneaded mixture having a moisture content of less than 7%, shaping the resultant mixture into the form of granules, pellets or the like and drying at a temperature below 70* C.

United States atent 1 1 Yamauchi 1 51 Dec. 30, 1975 PRODUCTION OFFREE-FLOWING PARTICLES OF GLUCOSE, FRUCTOSE OR THE MIXTURE THEREOFInventor: Toshio Yamauchi, Kyoto, Japan Daiichi Seiyaku Co., Ltd.,Kyoto, Japan Filed: May 31, 1974 Appl. No.: 475,198

Assignee:

Foreign Application Priority Data June 4, 1973 Japan 48-63250 US. Cl.127/58; 127/30; 127/63 Int. Cl. C13K l/00; C13K 9/00 Field of Search127/30, 58, 60, 63

References Cited UNITED STATES PATENTS 5/1970 Kusch 127/60 X 3,816,1756/1974 Melaja 127/58 X Primary Examiner-Morris O. Wolk AssistantExaminer-Sidney Marantz Attorney, Agent, or Firm-James C. Haight 13Claims, 1 Drawing Figure US. Patent Dec. 30, 1975 52 & $5 Q? kirsiq heREES SUGAR CONCENTRATION (75) PRODUCTION OF FREE-FLOWING PARTICLES OFGLUCOSE, FRUCTOSE OR THE MIXTURE THEREOF This invention relates to amethod of production of anhydrous powders, pellets or granules ofglucose, fructose or a mixture thereof. More particularly, it relates toa method whereby aqueous solutions containing glucose, fructose ormixtures thereof are converted into the form of dry powders, pellets,granules or the like without subjecting the-solution to acrystallization step.

Fructose or mixtures thereof with glucose are widely consumed in theform of a dry powder or solution. Although anhydrous crystallinefructose has been used even for dietary purposes, it is not essentialthat the fructose used for such purposes be pure, but rather a supply offructose as cheap as possible in large quantities is more important whenits nutritional value is taken into consideration. Fructose can also beproduced from glucose by the action of the enzyme glucose isomerase. Atequilibrium, the reaction mixture contains 43% fructose and 57% glucosebut is very hygroscopic and difficult to crystallize. Therefore, theisomerized products are used as sweeteners for confectionaries and otherfood products in the form of a syrup. However, the syrup has certaindisadvantages in that it is susceptible to deterioration due tocoloration, microorganism growth or partial crystallization in winter onstorage. It is, therefore, desirable to convert the syrup to afree-flowing solid which may find wide use in various fields,particularly in houshold consumption.

In my co-pending U.S. application Ser. No. 435,525 filed Jan. 22, 1974,a method of crystallization of anhydrous fructose has been disclosed.Crystallization of fructose according to the method described in saidU.S. application or otherwise always accompanies formation ofsubstantial amounts of green syrup, since the crystals are alwayspresent at equilibrium with the syrup regardless whether they are thefirst, second or third crops. The sugar concentration in the syrupdecreases as the crop proceeds, for instance, to about 85%. About 20% ofthe starting fructose content remains in the syrup when 80% of thestarting fructose has been recovered as crystals through the overallcrops. Thus it becomes difficult and uneconomical to subject such syrupto further crystallization step. If the syrup can be converted to afree-flowing, dry solid suitable for dietary uses, the advantages of theabove method will be greatly enhanced.

Attempts to dehydrate concentrated fructose solutions by means of sprayor film-drying have been unsuccessful.

In Japanese patent publication No. 15647 of 1971 corresponding to U.S.Pat. No. 3,513,023, a method of producing crystalline fructose has beendisclosed. According to this method, fructose solutions having at leasta 95% concentration are further concentrated in vacuo to a water contentfrom 2 to 5%, and then cooled to from 60 to 85C. A large quantity offructose crystals is added to the solution and the mixture is stirred ata temperature of 60 to 85C until it becomes a soft mass. The mass ismade solid, ground and dried at a temperature below 65C. This method hasthe difficulty of concentrating fructose to a concentration higher than95%. At concentrations higher than 90%, a fructose solution becomes veryviscous so that the evaporation rate decreases remarkably. Since alonger period of time or higher evaporation temperature is required toconcentrate the solution to 90-95% or higher, a change of color due topartial caramelization will unavoidably take place. In addition to thefact that a crystallization step is required, the necessary apparatusand energy used for mixing or kneading a very viscous semi-solid massmake this technique uneconomical. Furthermore, the resulting particlesproduced by a strong mixing under cooling must be converted to asuitable form such as pellets or the like. The application of thistechnique has been confined to fructose only.

An object of the present invention is to provide an economical method ofproducing free-flowing, anhydrous particles of glucose, fructose ormixtures thereof in such forms as powders, pellets, granules and thelike.

Another object is to provide a method whereby aqueous solutions ofglucose, fructose or mixtures thereof are converted into dry,free-flowing particles such as powders, pellets granules and the likewithout subjecting the. solution to a crystallization step.

Still other objects and advantages of the present invention will becomeapparent as the description proceeds. In a preferred embodiment of thepresent invention, crystals or powder of anhydrous glucose, fructose ormixtures thereof (hereinafter referred to as mother powder) are mixedand kneaded with a syrup or massecuite (hereinafter referred as syrup)containing 40 to 90%, preferably 60 to 90% of the same type of sugar asthe mother powder so that the mixture forms wet particles having amoisture content of less than 7%, preferably from 1.5 to 4%. This stepmay be conveniently carried out by charging the mother powder in akneader and adding the syrup gradually to the mother powder in amountssufficient to make the moisture content less than 7%. Alternatively, themother powder and the syrup may be mixed continuously by supplying themat a constant rate to a continuous mixer. This mixing may be carried outat room temperature or higher. Thus, hot syrup just withdrawn from avacuum evaporator (about C) can be mixed without cooling. During thismixing step, the mixture forms wet, round fine particles which are stillfree-flowing. At this stage, the mixture may easily be shaped into asuitable size of granules or pellets using a conventional type ofgranulator or pelletizer. The wet granules or pellets are then dried.Alternatively, the wet particles may be dried without subjecting them toa granulating or pelletizing ste 'l he resulting particles, granules orpellets are dried at a temperature below 70C, preferably at about 60C,under reduced pressure, for example at 10mm Hg. Other drying methodssuch as air-blowing or fluid drying may also be applied. In this case,air is preferably dehumidified to an absolute humidity less than about0.0lg of water per g. of air and heated from 50C to 70C.

The resulting products are free-flowing particles or pellets having anaverage particle size from 0.05 to 0.3mm. The granules preferably have acylindrical form of 0.5 to 1.5mm in diameter and about 2mm in length.

Although the finished products are generally uniform in shape and size,it is sometimes desirable to sieve the product through a screen. As canbe seen from the foregoing description, it is essential for the presentinvention that the mixture of the mother powder and the syrup has amoisture content less than 7%. At a moisture content higher than 7%, themixture is a mud which turns into an aqueous solution of sugar onheating during the subsequent drying step. Thus, drying into solidparticles becomes impossible. I

The relationship between the mixing ratio and the concentration of thesyrup to give the requiredrange of the moisture content is shown in theaccompanying drawing.

In the drawing the concentration of syrup is represented on thehorizontal axis and the ratio of the weight of syrup to the weight ofmother powder is represented in the vertical axis. Curve AB representsthis ratio at varying concentrations of syrup to give a 7% moisturecontent, and curves A B and C D are those of 4% and 1.5% moisturecontents respectively. The present invention is carried out within therange defined by points A, B, C and D, preferably the range definedpoints A, B, C, and D in the drawing.

Within this range, the weight of mother powder Wp, the weight of syrupWs and the percentage of water content in the syrup Xs are in therelationship represented by the following equations: Ws Xs/Wp Ws 7, orpreferably, 1.5 Ws Xs/Wp+Ws 4 out at a sugar concentration of syrupbetween 40% and 95%. At a concentration less than 40%, the mother powdermust be used in a very large quantity. When the concentration exceedsthe upper limit, the viscosity of the syrup increases too high todisperse the resulting mixture uniformly. Therefore, the sugarconcentration is preferably from 40 to 90% by weight of glucose,fructose or a mixture thereof.

Consequently, the ratio of the quantities of the syrup to the motherpowder, the sugar concentration of the syrup and the moisture content ofthe mixture of the mother powder with the syrup are less than 130% byweight, less than 95% by weight and less than 7% by weight, perferablyto 65% by weight, 40 to 90% by weight and 1.5 to 4% by weightrespectively.

Although the finished products produced'by the present invention have asufficient strength against crushing, binders such ascarboxymethylcellulose or sodium alginate, and/or lubricants such assugar ester with higher alkanoic acid may be used.

As the syrup, not only aqueous solutions of glucose, fructose ormixtures thereof but also the corresponding massecuite may be used. Inthe latter case, 30 to 50% of the total sugar must be present in theform of crystals and the quantity thereof should be included in thequantity of the mother powder. Other examples of the syrup are greensyrup separated from the massecuite as mentioned (sugar concentration 80to 90%), or syrup produced by the isomerization of glucose withion-exchanger or enzyme followed by concentrating to a concentrationfrom 70 to 90%. Invert sugar made from sucrose may also be employed. Thestarting mother powder may be anhydrous crystals of the same type ofsugar as mentioned. The particle size of the crystals is preferably0.005 to 0.3mm. Alternatively, the finished product which issubstantially free from water is advantageously used as the motherpowder in the subsequent cycle of the operation.

It is one of the advantages of the present that the sugar need notalways be the same in the syrup and the mother powder used. Thus, thesyrup obtained invention .mercially available isomerized glucosesolution with pure anhydrous fructose crystals.

The method of the present invention may preferably be practiced byreturning a part of the finished product corresponding to the amount ofmother powder used in the previous cycle to the subsequent cycle as themother powder therefor. This recycling of mother powder can be conductedeither in batch type or continuous operation. Thus, the finished productmay be withdrawn from each cycle of the operation in an amountcorresponding to the sugar content of the syrup. During the cycle ofoperation, sugar is not deteriorated because the drying is carried outat a temperature below C.

It is surprising the mixtures of fructose and glucose can satisfactorilybe solidified in the form of free-flowing particles in accordance withthe present invention, because the mixtures have heretofore beenconsidered to be too hygroscopic to dry up into such forms.

' The following examples are offered for illustrative purposes only, andare not intended to limit the scope of the present invention, which isdefined in the claims below. 7

EXAMPLE 1 charged in the kneader. 0.8 kg of an 83.8% aqueous solution ofsugar consisting of 98.7% of fructose and 1.3% of glucose was added tothe powder. After 10 to 15 minutes kneading, the resulting mixturebecame wet, free-flowing aggloinerates of crystals. The mixture retained2.79% of water and the purity of fructose therein was 99.7%. The mixturewas granulated by extruding through a screen at room temperature, andthe granules were dried in a vacuum chamber at lOmm Hg and 65C for 4hours. Free-flowing granules having a moisture content of 0.10% and anapparent density of 0.53 g/ml were obtained.

EXAMPLE 2 parts by weight of dried granules obtained in I Example 1 wasmixed with 38 parts by weight of anhydrous glucose. The mixture waspulverized to fine particles of 50 mesh (Tyler). 4.0 kg of the resultingpowder (moisture content 0.25%) was kneaded as in Example 1 with 1.55 kgof the same syrup as used in Example 1. The resulting mixture having' amoisture content of 3.0% was pelletized to small pellets using alaboratory type rotary disc-pelletizer at room temperature. The 7resulting freefflowingwet pellets were dried as in Example l.Free-flowing pellets having moisture content of 0.17 and an apparentdensity of 0.59 g/ml were obtained.

EXAMPLE 3 In this example, the mother powder and the syrup werecontinuously mixed using a double screw type continuous mixer. The sametype of sugar powder as used in Example 2 (particle size less than 50am,moisture content 0.19%) and a 12.2% solution of isomerized glucose(fructose 70%, glucose 30%) were supplied at a ratio 4:0.76 parts byweight. The mixture passed through the mixer for about 15 minutes. Theresulting mixture containing 2.14% of water was granulated and thegranules were dried as in Example 1. Free-flowing granules having amoisture content of 0.05% and an apparent density of 0.49 g/ml wereobtained.

EXAMPLE 4 Example 1 was repeated with the exception that 4 kg of drysugar powder consisting of 98.5% of fructose and 1.5% of glucose(moisture content 0.15%) and 0.92g of an 88.7% solution of enzymaticallyisomerized glucose (fructose 46.5%, glucose 53.5%) were used. Thekneaded mixture containing 4.1 1% of water was granulated and dried invacuo. Free-flowing granules having a moisture content of 0.15% and anapparent density of 0.54 g/ml were obtained.

EXAMPLE 5 Example 1 was repeated with the exception that 4 kg of a mixedsugar powder of fructose and glucose (7:3, moisture content 0.21%) and0.4 kg of the same syrup as used in the Example 4 were mixed. Theresulting mixture containing 2.13% of water was pelletized by the samemanner as Example 2 and then dried. Freeflowing pellets having amoisture content of 0.21% and an apparent density of 0.54 were obtained.

EXAMPLE 6 Example 1 was repeated with the exception that 4 kg of amixture of fructose and glucose (7:3, moisture content 0.21) and 1.20 kgof an 87.6% solution of the same sugar were mixed. The resulting mixturecontaining 3.03% of water was granulated and dried. Free flowinggranules having a moisture content of 0.08% and an apparent density of0.54 g/ml were obtained.

Various other examples and modifications of the foregoing examples canbe devised by the person skilled in the art after reading the foregoingdisclosure and the appended claims without departing from the spirit andscope of the invention. All such further examples and modificationsthereof are included within the scope of said claims.

What is claimed is:

1. A method for preparing anhydrous, free-flowing solid particles of asugar selected from the group consisting of glucose, fructose andadmixtures thereof, which comprises:

a. kneading an anhydrous powder of said sugar with a 4090% by weightsolution of said sugar in an amount of 5-65% by weight of said powderwithin the area shown between points A, B, C and D of the attachedDrawing without subjecting said solution to a crystallization step toform a kneaded mixture having a moisture content of less than 7% byweight;

b. shaping said kneaded mixture into particles; and

c. drying the shaped particles at a temperature lower than C. to formanhydrous particles.

2. A method according to claim 1, wherein said particles are in the formof granules.

3. A method according to claim 1, wherein said particles are in the formof pellets.

4. A method according to claim 1, wherein said sugar is fructose.

5. A method according to claim 1, wherein said sugar is invert sugar.

6. A method according to claim 1 wherein said sugar solution is amassecuite wherein 3050% of the total sugar is present in the form ofcrystals.

7. A method according to claim 1 wherein said sugar solution is greensyrup having a sugar concentration of -90%.

8. A method according to claim 1, wherein said moisture content is from1.5 to 4%.

9. A method according to claim 8, wherein said anhydrous sugar powderhas a particle size from 0.005 to 0.3mm.

10. A method according to claim 1, wherein said anhydrous sugar powderhas a particle size from 0.005 to 0.3mm.

11. A method according to claim 10, wherein said anhydrous sugar powderis made from the finished product of a previous cycle.

12. A method according to claim 1, wherein said sugar is isomerizedglucose.

13. A method according to claim 12 wherein said sugar solution has asugar concentration of 70-90%.

UNITED STATES PATENT AND TRADEMARK OFFICE CETIFICATE OF CORRECTIGNPATENT NO. 3 ,929,503

DATED December 30 1975 INVENTOR(S) 1 TOSHIO YAMAUCHI It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

1E THE HEADING Line 5, Assighee: "Daiichi Seiyaku Co., LTD., Kyoto,Japan" should be -Dai-Ichi Kogyo Seiyaku Co., Ltd., Kyoto, Japan--Signed and Sealed this thirteenth D ay Of April 1 9 76 [SEAL] A ttest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer (mnmixsirmvr uj'lau'msand T radcmarks

1. A METHOD FOR PREPARING ANHYDROUS, FREE-FLOWING SOLID PARTICLES OF ASUGAR SELECTED FROM THE GROUP CONSISING OF GLUCOSE, FRUCTOSE ANDADMIXTURES THEREOF, WHICH COMPRISES: A. KNEADING AN ANHYDROUS POWDER OFSAID SUGAR WITH A 40-90% BY WEIGHT SOLUTION OF SAID SUGAR IN AN AMOUNTOF 5-65% BY WEIGHT OF SAID POWDER WITHIN THE AREA SHOWN BETWEEN POINTSA, B, C AND D OF THE ATTACHED DRAWING WITHOUT SUBJECTING SAID SOLUTIONTO A CRYSTALLIZATION STEP TO FORM A KNEADED MIXTURE HAVING A MOISTURECONTENT OF LESS THAN 7% BY WEIGHT; B. SHAPING SAID KNEADED MIXTURE INTOPARTICLES; AND C. DRYING THE SHAPED PARTICLES AT A TEMPERATURE LOWERTHAN 70*C. TO FORM ANHYDROUS PARTICLES.
 2. A method according to claim1, wherein said particles are in the form of granules.
 3. A methodaccording to claim 1, wherein said particles are in the form of pellets.4. A method according to claim 1, wherein said sugar is fructose.
 5. Amethod according to claim 1, wherein said sugar is invert sugar.
 6. Amethod according to claim 1 wherein said sugar solution is a massecuitewherein 30-50% of the total sugar is present in the form of crystals. 7.A method according to claim 1 wherein said sugar solution is green syruphaving a sugar concentration of 80-90%.
 8. A method according to claim1, wherein said moisture content is from 1.5 to 4%.
 9. A methodaccording to claim 8, wherein said anhydrous sugar powder has a particlesize from 0.005 to 0.3mm.
 10. A method according to claim 1, whereinsaid anhydrous sugar powder has a particle size from 0.005 to 0.3mm. 11.A method according to claim 10, wherein said anhydrous sugar powder ismade from the finished product of a previous cycle.
 12. A methodaccording to claim 1, wherein said sugar is isomerized glucose.
 13. Amethod according to claim 12 wherein said sugar solution has a sugarconcentration of 70-90%.